A lithium ion battery is used as a small battery with a high energy density. The application of a lithium ion battery is further expanding. In addition, a high-performance lithium ion battery is demanded.
Patent Document 1 discloses a sealed electrochemical device. This device includes a lithium battery using an electrolytic solution. The device comprises a rectangular parallelepiped-shaped metal box having an opening end, and a resin lid. The metal box and the resin lid are connected by caulking so as to prevent leakage of an electrolytic solution.
Among lithium ion batteries, an all-solid-state battery in which the electrolytic solution is replaced by a solid electrolyte is particularly attracting attention, because in an all-solid-state battery, a solid electrolyte is used instead of the conventional electrolytic solution and it can therefore be expected that the energy density is further increased.
For example, Patent Document 2 discloses an all-solid-state battery in which an all-solid-state battery element obtained by disposing a solid electrolyte to intervene between a positive electrode and a negative electrode is covered by an outer casing. The outer casing of the all-solid-state battery is composed of a resin.
Patent Document 3 discloses a non-aqueous lithium ion battery. This is a battery where an all-solid-state battery element is housed in a metal outer casing.